The objective of the proposed research is to evaluate the effects of saphenous vein bypass graft surgery as compared to medical treatment in patients with chronic, stable angina pectoris using a prospective, randomized study format. The study has been in progress for 5 years with 98 patients randomly allocated to medical or surgical therapy. All patients undergo extensive clinical evaluation and studies, including exercise stress testing, echocardiography, hemodynamic and myocardial metabolic studies, coronary angiography and left ventriculography at the time of entry. These investigations are repeated in all patients six months after entry, and clinical evaluation is continued biononthly. Preliminary results after a 30 month mean follow-up show significantly greater functional improvement in surgical patients, but no difference in mortality or morbidity when compared to medically treated patients. The current proposal provides for long-term follow-up of these patients. Clinical outpatient examinations will continue bimonthly, with exercise stress tests and echocardiography annually. Coronary angiography, left ventriculography, hemodynamic and myocardial metabolic studies will be repeated five years after entry. The long-term goal is to evaluate the influence of saphenous vein bypass surgery on functional status, exercise capability, chemical evidence of myocardial ischemia, left ventricular function, the coronary circulation, and subsequent cardiac events including unstable angina pectoris, myocardial infarction and death.